Documentation regarding tempest cleanup can be found at the following link: https://docs.openstack.org/tempest/latest/cleanup.html
When init_saved_state and dry_run variables are set to false, the role execution will run tempest cleanup which deletes resources not present in the saved_state.json file.
The role can be also used for verification that tempest tests don't leak any resources or to test that 'tempest cleanup' command deleted all leaked resources as expected. Either way the role needs to be run first with init_saved_state variable set to true prior any tempest tests got executed. Then, after tempest tests got executed this role needs to be run again with role variables set according to the desired outcome: